This invention relates to etching and more particularly to an apparatus for selectively jet etching a plastic which is encapsulating an article, such as an epoxy encapsulated monolithic integrated circuit assembly chip, so that a preselected portion of the encapsulating material (i.e., the encapsulant) can be removed, exposing the previously encapsulated article, so that the article can be tested, used, studied and the like.
Before the advent of the instant invention, prior art de-encapsulation techniques consisted of either immersing the entire encapsulation in a container of etchant, or of mechanically removing selected portions of the encapsulant and then immersing the article together with the remaining adhering encapsulant in an etchant.
Both of these techniques resulted in overall damage to the exterior of the article that had been encapsulated. The exterior damage was of such a nature that it precluded subsequent operation of the article. In addition, mechanical agitation of the etchant was minimal, and incomplete removal of the plastic encapsulant often occurred. Further, the safety of personnel using these prior art techniques was endangered because they were exposed, of necessity, to open containers of hazardous chemicals.